The embodiments relate to a method as well as to system components for transmitting data in packets in a radio communications system.
Third generation radio communications systems (3G), in particular the UMTS (Universal Mobile Telecommunications System), which is standardized within the scope of 3GPP (3rd Generation Partnership Project), are increasingly moving toward the packet-oriented transmission of data and, in particular, voice for a more efficient use of the radio frequency resources which have a limited availability.
In this context, extensions to the UMTS standard HSDPA (High Speed Downlink Packet Access) and HSUPA (High Speed Uplink Packet Access), also known as E-DCH (Enhanced Dedicated Channel), were specified for instance. The E-DCH has a plurality of so-called control channels here, such as are described inter alia in more detail in the technical specification 3GPP TS 25.309 V6.5.0 “FDD Enhanced Uplink; Overall description; Stage 2 (Release 6)”. By way of example, the E-DCH has the so-called E-HICH-channel, which is transmitted in the downlink direction DL and contains positive and/or negative confirmations, so-called ACK/NACK (acknowledged/not acknowledged) signalings for data packets sent in the uplink direction UL. The E-DCH also has the so-called E-RGCH channel, which contains relative confirmations and/or scheduling commands for a group of terminals in the downlink direction. These two control channels are considered in more detail below, however further channels known to the person skilled in the art, in which the embodiments can be deployed advantageously, are included within the scope herein.
If the afore-described channels are to be used within the scope of a transmission of voice data for instance, in the form of a VoIP service (Voice over Internet Protocol) for instance, or also for other packet data services with a comparatively low data rate, this disadvantageously results, according to the current configuration of these channels, in a significant additional loading of the limited radio resources. By way of example, a dedicated resource of the E-HICH channel is currently assigned to each user of the E-DCH. This user-specific resource consists, in the example of the E-HICH, of a combination of a spreading code with spreading factor 128 and one of 40 possible orthogonal signatures. According to technical specification 3GPP TS 25.211 V6.7.0 “Physical Channels and Mapping of Transport Channels onto Physical Channels (FDD) (Release 6)”, an information bit can as a result be transmitted simultaneously to up to 40 users in each instance and clearly assigned to the respective receivers. In the case of the E-HICH, the above-described statuses ACK/NACK are signaled in this way with each bit for a specific user of the E-DCH.
The same method and the same resources are also used for the above-mentioned E-RGCH, with, in this case, an E-RGCH also not necessarily being assigned to each user and/or a common E-RGCH being assigned to a respective group of users, i.e. the users of this group adhere to the same relative confirmation commands. In the instance, however, that the user is assigned both an E-HICH as well as an E-RGCH, this indicates a further restriction to the user who is addressable by each physical channel and/or spreading code, i.e. a physical channel is to be provided for each 20 users.
For above-mentioned services, such as VoIP or a low-rate packet data transmission to a large number of users, this would, however, mean that five spreading codes alone have to be assigned to 100 users for instance for the transmission of signaling confirmations, which results in a significant restriction in the transmission capacity for the user data transmission in the downlink direction.